1. Field of the Invention
The present invention relates to a light-solubilizable composition suitable for producing lithographic printing plates, IC circuits and photo-masks.
In greater detail, it relates to a light-solubilizable composition comprising an o-quinonediazide compound, an alkali-soluble resin and insoluble fine particles having a hydrophobic surface.
2. Description of the Prior Art
Hitherto, light-solubilizable compositions comprising o-quinonediazide compounds and alkali-soluble resins have been used for the production of lithographic printing plates or as photo-resists because of their excellent properties. However, these light-solubilizable compositions have the drawback of insufficient physical strength in the case of forming a coating films, particularly, if scratches are found on the coating films they are magnified by the development, or the drawback that the amount of composition processable with a prescribed amount of a developing solution (development processing ability) is insufficient; consequently, a large amount of developing solution is required.
Further, coating films formed using these light-solubilizable compositions must be developed under exacting conditions (low development tolerance), i.e., precise control of alkali concentration in the developing solution, temperature of the developing solution and developing time are required, which is very difficult.
To overcome these drawbacks, various attempts have been made. For example, in Japanese patent application (OPI) No. 8128/78 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), it is proposed to use fillers such as talc powder, glass powder, clay, starch, wheat powder, corn powder or Teflon powder, etc., in order to improve the strength of a coating film. However, these conventional fillers do not extend development tolerance and most of them have the drawback that printing inks adhere to image areas in the case of use as a lithographic printing plate only with difficulty.
Further, when the ratio of o-quinonediazide compound(s) in the light-solubilizable composition is increased, though the development tolerance is widened and development processing ability is improved, sensitivity deteriorates.
On the other hand, as described in U.S. Pat. No. 4,115,128, if cyclic acid anhydrides are added to such light-solubilizable compositions, sensitivity is improved without changing development tolerance and development tolerance is improved without changing sensitivity by increasing the amount of o-quinonediazide compounds. However, such a technique has the drawback that when the amount of o-quinonediazide compounds is increased to provide sufficient development tolerance, the amount of cyclic acid anhydrides must be greatly increased in order to prevent a deterioration of sensitivity, whereby the physical strength of a coating film deteriorates.
Further, it is known from U.S. Pat. No. 4,115,128 to add pigments to light-solubilizable compositions comprising quinonediazide compounds and alkali-soluble resins to provide colored images. Although the addition of pigments improves image coloring, such technique has the drawback that when the amount of pigment is increased to improve coating film physical strength, sensitivity remarkably deteriorates or printing-out images are difficult to see when using a photosensitive lithographic printing plate having light-fading printing-out capability (capability that visible images are obtained after exposure without developing) because of the color of the pigment(s).